Improving geoexchange systems

New guidelines set best practice standard to ensure successful geoexchange projects

Friday, March 27, 2015

by Ruben Arellano

Geoexchange and heat pump technology is long established, with the first systems developed and implemented in the 1950s. With increasing awareness, improved equipment and industry expertise, and the rising cost of energy in recent years, the technology has experienced a resurgence. It is estimated that there are now more than 100,000 geoexchange systems installed in Canada, and in the past 10 years the industry has experienced double-digit growth in most markets across the country.

While deceptively simple, geoexchange technology relies on the integration of mechanical components to adapt to complex site-specific earth and building thermodynamic processes. The system’s long-term viability and performance require a rigorous and thorough design approach based on science and judgment, quality construction by experienced trades, and a complete and detailed system commissioning.

Those working on a geoexchange project for the first time may be unaware of the complexities of geoexchange design and construction. A province like B.C. has an extremely variable geography, climate, and building demographics requiring that each project design is unique and site-specific. Thorough and expert information tailored to each region is needed to ensure that systems meet the needs and expectations of owners and proponents in terms of their specific environmental, social, and financial benefit targets.

A challenge in the current market is a lack of thorough and verifiable data on the performance of operating systems. While plenty of geoexchange systems have operated without trouble for years, an unacceptable number of systems (heard of anecdotally) are underperforming. There are also systems that have had difficulties in the implementation.

The following examples illustrate situations that can arise:

A care home developer receives a development permit that requires geoexchange technology to be included. The developer juggles complex competing design schedules, but the geoexchange system’s scope for design and construction is procured late in the building design when site preparation is already underway. The result is hurried design and construction, with little ability to optimize cost-effective design and performance criteria.

A municipal hall is designed to incorporate a geoexchange system, and design concepts and budgets are developed without consulting a geoexchange engineer or completing an adequate site intrusive investigation. A drilling contract is awarded, and the contractor encounters challenging conditions for their equipment and submits a claim for extra fees. A dispute arises and building design and construction schedules are put at risk.

A prime contractor for an institutional project acts as a design coordinator and separately subcontracts the geoexchange system’s engineering, drilling, heat pump installation, building mechanical, and controls components, in an effort to control costs and use preferred service providers. The process results in a patchwork design with no whole-system design approach, and the maintenance contractor is left struggling to operate the costly and complex system.

Given the variability and complexity of applying geoexchange technology in B.C., and recognizing the reported gap between expectations and performance for some geoexchange projects, there has been a call for more detailed B.C. specific technical materials that will help ensure these situations are avoided.

As a result, Geoexchange BC has recently published a series of guidelines (“Professional Guidelines for Geoexchange Systems in British Columbia”, www.geoexchangebc.com) to educate key players (developers, owners, coordinating professionals, construction managers, engineers, installers and commissioning teams) on the requirements of a successful geoexchange project.

These guidelines also help establish a strong standard of practice for the industry going forward. Each guideline covers a separate topic and is focused on commercial-scale applications within B.C., although many of the concepts are applicable to smaller projects and other regions.

There are four guidelines in the current series:

Part 1: Assessing Site Suitability and Ground Coupling Options

Part 2: Design

Part 3: Commissioning

Part 4: Procurement

A User Guide summarizes the key content of each guideline, provides a flowchart and checklist format for guidance and record-keeping, and identifies topics within the guideline relevant to each key player on the project team.

The package comprises more than 250 pages of detailed, purpose-written literature and sample forms. It has collectively been written by 20+ active industry experts, with review and editing by more than 40 industry review panelists. It has been directly funded and approved by government agencies at the municipal, provincial and national level, as well as major provincial utilities. It is a unique resource in Canada, and no doubt North America.

Studies and feedback have demonstrated that where a thorough and thoughtful process is taken towards geoexchange systems’ selection, design, construction, commissioning and operation, they deliver energy and cost savings that meet, and often exceed, original expectations. It is the hope of Geoexchange BC that by sharing the knowledge assembled within the guidelines and setting a standard for best practice, all future projects can be similarly successful.

Well-designed geoexchange systems are a proven and reliable solution to boost energy efficiency and reduce carbon emissions, and have attracted significant attention. However, failure to adequately design, install, commission, and control a geoexchange system will result in significantly reduced performance and undo the business case for making the investment in geoexchange.

Ruben Arellano, P.Eng. is past chair and currently a director with GeoExchange BC, a not-for-profit organization dedicated to the education, promotion and responsible design and installation of geoexchange systems. He is also a district energy specialist with Associated Engineering in Burnaby, B.C.